Phosphorofilm is an aqueous solution of a polymer
containing phosphorous which may be applied to silicon wafers
either by spraying or spinning.

Physical Characteristics
Viscosity 7 cp @ 25oC
Density 1.01

Contaminant Limits
Na, Fe, Zn, Cu, Au, Mn, Ni < 1 ppm

Application Notes
Films may be deposited either by spinning or spraying. Spinning
at 3000 rpm will yield a film about 3200 angstroms thick. Film
deposited by spraying will exhibit excellent leveling
characteristics. Film thickness obtained by spraying will depend
upon such variable as the liquid flow rates, determined by liquid
pressure, and rate of travel of the substrates under the spray
nozzle. Typical conditions are as follows:

Films deposited by spinning are ready for diffusion. Films
deposited by spraying should be heated to 40-50oC to
insure drying.

Diffusion
Diffusion is carried out in nitrogen atmosphere with 1-2% oxygen.
Typical results for one hour diffusion are as follows:

Temperature

Rs
(ohms/sq.)

Xj
(microns)

850oC

45

0.05

875oC

35

0.1

900oC

30

0.5

950oC

20

0.7

After diffusion films which remain on the wafer surface are
readily etched away in dilute HF solution.

Cleaning
All apparatus used with this solution may be cleaned in warm
water.

Safety Considerations The solution is essentially
non-flammable. The phosphorous concentration is such that the
material should not be ingested. Eye protection should be used,
since the solution is acidic. During the diffusion process, in
addition to CO2, oxides of phosphorous will be
evolved. At room temperature the only volatile is H2O.
Since no toxicity studies have been carried out with this
product, it should be treated with care as with any laboratory
chemical.